Various devices and instruments have been proposed for exercising the lungs in order to increase lung capacity and improve pulmonary functions. Such devices usually require the patient to exhale or inhale through a mouthpiece, and often incorporate some visible means for observing the capacity of the participant, for example, by a meter or an article that is displaced by passage of gas through the device as the user exhales or inhales. Preferably, the visible means is one which can be observed by the user which will tend to increase participation and interest in the exercise.